IBM 5150 Technical Reference page 48

+5V
74LS38
8253 Timer # 2 t O
Output
OR
o
0--------------__
0.678V
to AUX
Input
0--------------___
0.075V
to MIC
Input
GND
Cassette Interface Write Hardware Block Diagram
+5V
I
+5V
4.7
kOhm
SN75475
Relay
+5V- Clamp
N/O
S
Coil
C~.
Cassett
e
~8
OR
In
VCC
Out
f-­
Coil
Motor
Control
Motor-[O
On 0
r - -
VSS
Com
" ­
GND
Cassette Motor Control Block Diagram
System Board 1-29